The present invention is directed to a railway car truck having a pair of side frames and a bolster and a transom extending transversely between the side frames, wherein a respective rocker seat is rigidly and permanently attached to each end of the transom and is pivotally supported on a rocker bar that is supported by the tension member of a side frame.
The railway car truck described in U.S. Pat. No. 3,670,660 was developed to address problems of lateral instability of railway car trucks due to truck hunting at high speed service, to provide a smooth ride and to reduce maintenance. The railway car truck of U.S. Pat. No. 3,670,660 provides hunting-free operation by using the side frames of the truck as swing hangers and by interconnecting the side frames with a transom to rigidize the truck to increase lozenging stiffness.
Over the last several years developments in railway car construction has made the cars lighter, such that additional restraint is required in the side frame to transom connection to prevent hunting. Bolting of the transom to the rocker seats is one way to introduce additional restraint. However, in the railway car truck of U.S. Pat. No. 3,670,660, this can only be done after the rocker seats and transom are separately assembled into the side frames of the truck. This leaves room for potential assembly errors. If the truck is not one-hundred percent square at the time of assembly, the tolerances in the bolt holes in the rocker seat and in transom could permit an out of squareness (lozenging) of 0.4056 inch across the rail. A condition like this could lead to one-sided flange contact of the truck wheels with the rail and resulting wear to the wheels. The surface conditions of the rocker seats and of the transom at their interface can also further alter the correct and desired amount of restraint therebetween. The present invention provides the desired amount of restraint between the transom and rocker seat and enables the railway car truck to operate hunting-free without lozenging and allows the rocker seats to be preassembled to the transom.
A railway car truck having first and second side frames that are spaced apart and parallel to one another, and a bolster and a transom that extend transversely between the first and second side frames. Each side frame includes a central axis, a bottom tension member, a top compression member, first and second spaced apart columns extending between the bottom tension member and the top compression member, and a window located between the bottom tension member and the top compression member and between the first and second columns. The transom includes a first end, a second end and a central axis. Each end of a transom is located within a window of a respective side frame. Rocker connections pivotally support each end of the transom on the bottom tension member of a respective side frame. Each rocker connection includes a rocker seat attached to the end of the transom and a rocker bar removably supported on the bottom tension member of the side frame. The rocker seat includes a rocker bearing having a generally cylindrical-shaped concave bearing surface and a central axis. The central axis of the rocker bearing is perpendicular to the central axis of the transom. The rocker bar includes a generally cylindrical-shaped convex bearing surface adapted to pivotally engage the concave bearing surface of the rocker seat. The convex bearing surface of the rocker bar has a central axis located parallel to the central axis of the side frame. The pivotal engagement of the rocker bar with the rocker seat disposes the central axis of the transom perpendicular to the central axis of the side frame. The rocker bar and the side frame are pivotal with respect to the rocker seat and to the transom about the central axis of the rocker bar.
The railway car truck is assembled by attaching a rocker seat to each end of the transom such that the central axis of the bearing surface of each rocker seat is perpendicular to the central axis of the transom. The bolster is placed on top of the transom and generally parallel to the transom. The ends of the bolster and of the transom are inserted into a window of a side frame such that the transom is spaced apart from the bottom tension member of the side frame. The rocker bar is inserted through a passageway in the side frame to the window of the side frame where the rocker bar is placed under the rocker seat and within pockets on the bottom tension member of the side frame. The transom is lowered until the bearing surface of the rocker seat pivotally engages the bearing surface of the rocker bar. A plurality of springs are inserted between the transom and the bolster. The bolster is then lowered onto the springs.